scholarly journals Assessing the role of inversions in maintaining genomic differentiation after secondary contact: local adaptation, genetic incompatibilities, and drift

2020 ◽  
Author(s):  
Marina Rafajlović ◽  
Jordi Rambla ◽  
Jeffrey L. Feder ◽  
Arcadi Navarro ◽  
Rui Faria
Keyword(s):  
Computer Simulations ◽  
Empirical Data ◽  
Population Differentiation ◽  
Finite Population ◽  
Secondary Contact ◽  
Local Adaptations ◽  
Persistence Time ◽  
Chromosomal Inversions ◽  
Population Sizes

AbstractDue to their effects on reducing recombination, chromosomal inversions may play an important role in speciation by establishing and/or maintaining linked blocks of genes causing reproductive isolation (RI) between populations. These views fit empirical data indicating that inversions typically harbour loci involved in RI. However, previous computer simulations of infinite populations with 2-4 loci involved in RI implied that, even with gene flux as low as 10−8 between alternative arrangements, inversions may not have large, qualitative advantages over collinear regions in maintaining population differentiation after secondary contact. Here, we report that finite population sizes can help counteract the homogenizing consequences of gene flux, especially when several fitness-related loci reside within the inversion. In these cases, the persistence time of differentiation after secondary contact can be similar to when gene flux is absent, and notably longer than the persistence time without inversions. Thus, despite gene flux, population differentiation may be maintained for up to 100,000 generations, during which time new incompatibilities and/or local adaptations might accumulate and facilitate progress towards speciation. How often these conditions are met in nature remains to be determined.

scholarly journals DO LANGUAGE CHANGE RATES DEPEND ON POPULATION SIZE?

2008 ◽  
Vol 11 (03) ◽  
pp. 357-369 ◽  
Author(s):  
SØREN WICHMANN ◽  
DIETRICH STAUFFER ◽  
CHRISTIAN SCHULZE ◽  
ERIC W. HOLMAN
Keyword(s):  
Population Size ◽  
Computer Simulations ◽  
Empirical Data ◽  
Language Change ◽  
Strong Dependence ◽  
Language Model ◽  
Population Sizes

An earlier study [24] concluded, based on computer simulations and some inferences from empirical data, that languages will change the more slowly the larger the population gets. We replicate this study using a more complete language model for simulations (the Schulze model combined with a Barabási–Albert network) and a richer empirical dataset [12]. Our simulations show either a negligible or a strong dependence of language change on population sizes, depending on the parameter settings; while empirical data, like some of the simulations, show a negligible dependence.

scholarly journals Institutions for Simulations

2006 ◽  
Vol 19 (1) ◽  
pp. 35-51
Author(s):  
Ann Johnson
Keyword(s):  
Nanostructured Materials ◽  
Computer Simulations ◽  
Scientific Knowledge ◽  
Empirical Data ◽  
Close Coupling ◽  
Resource Needs ◽  
Nasa Ames Research ◽  
Cheap Alternative ◽  
Computational Nanotechnology

Computational nanotechnology is a simulation science; that is, a way of producing scientific knowledge dependent upon computer simulations because, for a variety of reasons, current experimental set-ups do not answer crucial questions. The resource needs of simulation science have often been obscured by two assumptions – that simulations are a ‘cheap’ alternative to experiment and that they are closely connected to theory – though not simply synonymous with or simple extensions of theory. This paper challenges both notions by exploring the resources - human, financial, and computational – needed to perform computational nanotechnology and by showing the close coupling between empirical data and the construction of simulations. I look specifically at three U.S. computational nanotechnology sites and projects: the NASA-Ames Research Center, the Network for Computational Nanotechnology at Purdue University, and the Chemical Industry’s Roadmap for Nanostructured Materials as a protocol for nanotechnological development that specifically addresses the role of simulations.

scholarly journals Recombination Can Evolve in Large Finite Populations Given Selection on Sufficient Loci

Genetics ◽  
2003 ◽  
Vol 165 (4) ◽  
pp. 2249-2258 ◽  
Author(s):  
Mark M Iles ◽  
Kevin Walters ◽  
Chris Cannings
Keyword(s):  
Experimental Evidence ◽  
Genetic Drift ◽  
Finite Population ◽  
Selective Advantage ◽  
Indirect Selection ◽  
Small Populations ◽  
Finite Populations ◽  
Population Sizes ◽  
Population Recombination

AbstractIt is well known that an allele causing increased recombination is expected to proliferate as a result of genetic drift in a finite population undergoing selection, without requiring other mechanisms. This is supported by recent simulations apparently demonstrating that, in small populations, drift is more important than epistasis in increasing recombination, with this effect disappearing in larger finite populations. However, recent experimental evidence finds a greater advantage for recombination in larger populations. These results are reconciled by demonstrating through simulation without epistasis that for m loci recombination has an appreciable selective advantage over a range of population sizes (am, bm). bm increases steadily with m while am remains fairly static. Thus, however large the finite population, if selection acts on sufficiently many loci, an allele that increases recombination is selected for. We show that as selection acts on our finite population, recombination increases the variance in expected log fitness, causing indirect selection on a recombination-modifying locus. This effect is enhanced in those populations with more loci because the variance in phenotypic fitnesses in relation to the possible range will be smaller. Thus fixation of a particular haplotype is less likely to occur, increasing the advantage of recombination.

Maximum fluid concentrations of materials released from platelets at a surface

1983 ◽  
Vol 244 (1) ◽  
pp. H109-H114 ◽  
Author(s):  
G. A. Adams ◽  
I. A. Feuerstein
Keyword(s):  
Platelet Aggregation ◽  
Empirical Data ◽  
Maximum Amount ◽  
Inhibit Platelet Aggregation ◽  
Fluid Concentration ◽  
Diffusion And Convection ◽  
Platelet Accumulation ◽  
Von Willebrand ◽  
Willebrand Factor

We examine the estimation of local concentrations of materials that are released from the dense and alpha-granules of platelets during accumulation of platelets upon collagen-coated glass. Platelet/red blood cell suspensions were perfused through a 1.3-mm-ID tube. Empirical data were used in a calculation procedure, based on diffusion and convection, designed to yield an upper bound on the interfacial fluid concentration (IFC) for each substance considered. The necessary empirical data are the rate of platelet accumulation and the maximum amount of material in the platelet capable of secretion. It was found that the IFC is dependent on the shear rate at the surface (G) and is proportional to G0.27. This means that an eightfold increase in flow rate would increase the IFCs approximately twofold. Serotonin, pyrophosphate, adenosine 5'-monophosphate (AMP), and adenosine 5'-triphosphate (ATP) were found not to be present in sufficient quantities to produce IFCs that could influence platelet aggregation if used alone at the IFC. A second set of materials, fibrinogen, fibronectin von Willebrand factor, and calcium, had IFCs less than their concentrations normally found in plasma. A third category, containing adenosine 5'-diphosphate (ADP) alone, had an IFC close to those known to affect platelet aggregation. The role of metabolites of arachidonic acid, which may promote or inhibit platelet aggregation, awaits further description.

Patterns of population differentiation in annual killifishes from the Paraná-Uruguay-La Plata Basin: the role of vicariance and dispersal

2012 ◽  
Vol 39 (9) ◽  
pp. 1707-1719 ◽  
Author(s):  
Graciela García ◽  
Verónica Gutiérrez ◽  
Julia Vergara ◽  
Pablo Calviño ◽  
Alejandro Duarte ◽  
...  
Keyword(s):  
Population Differentiation ◽  
La Plata ◽  
La Plata Basin

Exclusion of the Role of Secondary Contact in an Allele Frequency Cline in the Mussel Mutilus edulis

Evolution ◽  
1985 ◽  
Vol 39 (2) ◽  
pp. 432 ◽  
Author(s):  
Thomas J. Hilbish ◽  
Richard K. Koehn
Keyword(s):  
Allele Frequency ◽  
Secondary Contact

The evolving role of animal laboratories in physiology instruction

2005 ◽  
Vol 29 (3) ◽  
pp. 144-150 ◽  
Author(s):  
Alice W. Ra'anan
Keyword(s):  
Medical Education ◽  
Active Learning ◽  
Computer Simulations ◽  
Contributing Factors ◽  
Educational Impact

Laboratory exercises are intended to illustrate concepts and add an active learning component to courses. Since the 1980s, there has been a decline in animal laboratories offered in conjunction with medical physiology courses. The most important single reason for this is cost, but other contributing factors include the development of computer simulations, changes in medical education, and pressure from antivivisectionists. Unfortunately, the elimination of animal laboratories has occurred with relatively little consideration of the educational impact of this change. Although computer simulations are considered effective in helping students acquire basic physiological concepts, there is evidence some students acquire a more thorough understanding of the material through the more advanced and challenging experience of an animal laboratory. The fact that such laboratories offer distinct educational advantages should be taken into account when courses are designed.

A Study on the Prevalence and Nature of Ragging Practices in Selected Educational Institutions in India

2018 ◽  
Vol 15 (2) ◽  
pp. 187-202
Author(s):  
Mohan Rao ◽  
Shobna Sonpar ◽  
Amit Sen ◽  
Shekhar P. Seshadri ◽  
Harsh Agarwal ◽  
...  
Keyword(s):  
Empirical Data ◽  
Print Media ◽  
Institutional Factors ◽  
Educational Institutions ◽  
Critical Factors ◽  
Place Of Residence ◽  
The Media ◽  
Media Reports

Ragging has claimed hundreds of innocent lives and has ruined the careers of thousands of students. A total of 717 cases of ragging were reported in the English print media alone across the country from January 2007 to September 2013. However, the media reports tend to focus on extreme cases and do not reveal the true extent of ragging. Moreover, in the absence of empirical data, it is difficult to understand the processes involved in, and the ramifications of, ragging. This study examines the prevalence and types of ragging practices in educational institutions. The study covered 10,632 students from 37 educational institutions spread across 12 states in India. Findings show that almost 40 per cent students admitted to having experienced some kind of ragging. College-wise analysis of the results showed marked variations in the prevalence of ragging among colleges, thus pointing to the role of institutional factors in the occurrence of ragging. Variations in responses are also seen based on the kind of course pursued, gender, and place of residence of student, thus indicating that these are critical factors in influencing the prevalence, severity and kinds of ragging practices.

scholarly journals Empathic Behavior in Early Childhood under Condition of Taking the Mom’s Role in the Play

2018 ◽  
Vol 10 (4) ◽  
pp. 23-30
Author(s):  
T.O. Yudina
Keyword(s):  
Early Childhood ◽  
Prosocial Behavior ◽  
Empirical Data ◽  
Role Playing ◽  
Role Taking ◽  
Mediating Role ◽  
The Difference ◽  
Empathic Behavior

Following the modern theoretical and empirical data on the problem of relation between the role-taking and empathy abilities we supposed that empathic behavior in early childhood could be realized through acquiring the role “mom” within the role playing. In order to test our suppose we have conducted the ingroup experiment with 36 toddlers (M=35 months) and compared the frequency of the empathic behavior under two conditions: 1) taking the role of mom and 2) taking the role of friend by the toddler withing the experimental story-play with toys. According to our hypothesis we expected that children would display the empathic behavior more frequent in the condition of taking the mom’s role. Our hypothesis was not confirmed since the difference between conditions has been not significant. Such results reveal that the parental models do not serve significant mediating role in the child’s learning of prosocial behavior.

scholarly journals ANALISIS PERANAN USAHA KECIL DAN MENENGAH TERHADAP PENYERAPAN TENAGA KERJA DI KABUPATEN KEBUMEN

2019 ◽  
Vol 18 (1) ◽  
pp. 26-35
Author(s):  
Anton Prasetyo ◽  
Miftahul Huda
Keyword(s):  
Regression Analysis ◽  
Multiple Regression Analysis ◽  
Multiple Regression ◽  
Empirical Data ◽  
Small And Medium Enterprises ◽  
Research Data ◽  
Sales Volume ◽  
Test Tool ◽  
Medium Enterprises

This research aims to analyze the factors that influence the role of Small and Medium Enterprises (SMEs) on employment, namely capital, sales volume, type of business, length of business, and wages. Empirical data is presented to prove that the role of small and medium enterprises on employment is influenced by capital, sales volume, type of business, length of business, and wages. Multiple regression analysis through the SPSS program was used as a research test tool. The research data was obtained from SMEs businesses, Central Bureau of Statistics and the SMEs Office to test scientifically whether capital, sales volume, type of business, duration of business, and wages affect employment. Research results show that the duration of the business influences the absorption of labor while capital, sales volume, type of business, and wages do not affect employment. Keywords: SMEs, capital, sales volume, type of business, length of business, wages

Sign in / Sign up

Export Citation Format

Share Document